1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that can prevent interference between deposited dots when forming an image which comprises a plurality of dots.
2. Description of the Related Art
Conventionally, as an image forming apparatus, an inkjet printer (inkjet recording apparatus) is known which comprises an inkjet head (liquid ejection head) having an arrangement of a plurality of nozzles and which records images on a recording medium by ejecting ink from the nozzles toward the recording medium while causing the inkjet head and the recording medium to move relatively to each other.
In such an inkjet printer, there is a problem of so called “interference of deposited dots”, that is, a dot shape created by dots on a recording medium is deformed when the dots formed by ejecting adjacent liquid droplets overlapping to each other from the nozzles onto the recording medium.
In order to prevent such interference of deposited dots, an inkjet printer is proposed in which, of the plurality of numbers of ejections, a pre-established output waiting time (specifically, a waiting time for n times drum rotations) is inputted before depositing dots in the main scanning direction or sub-scanning direction so that the adjacent dots overlap to each other (see Japanese Patent Application Publication No. 2001-129982)
An inkjet printer is also proposed in which, when ejecting ink with different colors (for example, yellow and magenta) onto on section on the recording medium, the ejection is performed by the number of rotations of the drum (see Japanese Patent Application Publication No. 11-042799). In the case of using two colors, this object is achieved such that the time spent until dots in the both inks overlap can be increased by at least one rotation of the drum.
A configuration of inkjet printer is also proposed so that a time T until different color dots make contact with each other or a time T until overlap at deposited positions (namely, color overlapping time) is represented by T≧10 msec (see Japanese Patent Application Publication No. 2002-120361).
However, in the prior art, there is a problem that an image cannot be formed at high speed even if the interference of deposited dots is resolved.
Furthermore, in Japanese Patent Application Publication Nos. 2001-129982, 11-042799, and 2002-120361, there is no concrete description relating to technologies for preventing interference of deposited dots which are adjacent to each other in a state of overlapping to each other in the sub-scanning direction.
Moreover, in Japanese Patent Application Publication Nos. 2001-129982, 11-042799, and 2002-120361, there is no concrete description relating to technologies for preventing interference of deposited dots which are adjacent to each other in a state of overlapping to each other in the sub-scanning and main scanning directions.